The present invention relates to the art of computer driven printers, particularly color ink jet printers. Printers of this type have a printhead carriage which is mounted for reciprocal movement on the printer in a direction orthogonal to the direction of movement of the paper or other medium on which printing is to take place through the printer. The printer carriage of a color printer typically has a black ink and one or more color thermal ink jet printheads removably mounted thereon.
Provision must be made for transmitting printhead control signals and printhead position data to and from the moveable carriage. Two methods are presently used. The first method uses a rigid printed circuit board mounted on the carriage structure which receives multiplexed signals transmitted by a carriage trailing cable from the main logic board. The rigid PCB includes demultiplexing circuitry which then transmits the demultiplexed signals to a separate printhead interconnect which may be either (a) a separate flex circuit with compliant dimple contacts that interconnect with the thermal ink jet printheads or (b) a module that mounts on the carriage mounted PCB that consists of spring loaded plungers that engage the thermal ink jet cartridges. The rigid carriage borne PCB and separate flex circuit or module are expensive options that consume valuable space and mass which should be minimized on the moveable carriage.
The second method uses flexible cables extending from a printed circuit board mounted in a remote stationary position on the printer to the printhead carriage and transmit de-multiplexed signals to the carriage, the de-multiplexing circuitry being positioned on the printed circuit board. Apart from the fact that a considerably large number of individual conductors are required in the trailing cable when de-multiplexed signals are to be conducted thereby, the currently used de-multiplexed signal transmitting trailing cables comprise two separate superimposed layers which respectively transmit de-multiplexed signals to the black ink jet printhead and to the color printhead. In order to connect the various conductors of the two layers to the printed circuit board, four separate cable connectors are employed thus requiring the two superimposed layers of the cable each to be split at the PCB connection end into two separate spaced parallel sections. Fabrication of these trailing cables for transmitting de-multiplexed signals to the carriage is extremely expensive due to the large number of conductors required (typically 120) and the amount of unusable areas on a standard rectangular circuit fabrication layout.
The present invention provides a printhead de-multiplexing and interconnect carriage mounted flex circuit comprising:
a) a flexible multi-conductor carrying insulating panel foldable into a generally three sided configuration for attachment to a relatively rigid printhead carriage for conducting multiplexed electrical control signals to printheads mounted on and moveable with the printhead carriage, some conductors in said panel terminating in printhead electrical contacts on a surface thereof; PA1 b) a cable connecter on said panel in electrical contact with said conductors for connecting said flex circuit to a printhead trailing cable which extends to a remote location from which multiplexed printhead control signals are transmitted to said flex circuit; and PA1 c) at least one printhead control signal de-multiplexer components mounted on said flexible panel in electrical contact with at least some of said conductors.